/*
* Copyright 2008 ZXing authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*      http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

using ZXing.Common;

namespace ZXing.QrCode.Internal
{
   /// <summary>
   /// 
   /// </summary>
   /// <author>
   /// satorux@google.com (Satoru Takabayashi) - creator
   /// </author>
   internal static class MatrixUtil
   {
      private static readonly int[][] POSITION_DETECTION_PATTERN = new int[][]
                                                                      {
                                                                         new int[] { 1, 1, 1, 1, 1, 1, 1 }, 
                                                                         new int[] { 1, 0, 0, 0, 0, 0, 1 }, 
                                                                         new int[] { 1, 0, 1, 1, 1, 0, 1 }, 
                                                                         new int[] { 1, 0, 1, 1, 1, 0, 1 }, 
                                                                         new int[] { 1, 0, 1, 1, 1, 0, 1 }, 
                                                                         new int[] { 1, 0, 0, 0, 0, 0, 1 }, 
                                                                         new int[] { 1, 1, 1, 1, 1, 1, 1 }
                                                                      };

      private static readonly int[][] POSITION_ADJUSTMENT_PATTERN = new int[][]
                                                                       {
                                                                          new int[] { 1, 1, 1, 1, 1 }, 
                                                                          new int[] { 1, 0, 0, 0, 1 }, 
                                                                          new int[] { 1, 0, 1, 0, 1 }, 
                                                                          new int[] { 1, 0, 0, 0, 1 }, 
                                                                          new int[] { 1, 1, 1, 1, 1 }
                                                                       };

      // From Appendix E. Table 1, JIS0510X:2004 (p 71). The table was double-checked by komatsu.
      private static readonly int[][] POSITION_ADJUSTMENT_PATTERN_COORDINATE_TABLE = new int[][]
                                                                                        {
                                                                                           new int[] { -1, -1, -1, -1, -1, -1, -1 }, 
                                                                                           new int[] { 6, 18, -1, -1, -1, -1, -1 }, 
                                                                                           new int[] { 6, 22, -1, -1, -1, -1, -1 }, 
                                                                                           new int[] { 6, 26, -1, -1, -1, -1, -1 }, 
                                                                                           new int[] { 6, 30, -1, -1, -1, -1, -1 }, 
                                                                                           new int[] { 6, 34, -1, -1, -1, -1, -1 }, 
                                                                                           new int[] { 6, 22, 38, -1, -1, -1, -1 }, 
                                                                                           new int[] { 6, 24, 42, -1, -1, -1, -1 }, 
                                                                                           new int[] { 6, 26, 46, -1, -1, -1, -1 }, 
                                                                                           new int[] { 6, 28, 50, -1, -1, -1, -1 }, 
                                                                                           new int[] { 6, 30, 54, -1, -1, -1, -1 }, 
                                                                                           new int[] { 6, 32, 58, -1, -1, -1, -1 }, 
                                                                                           new int[] { 6, 34, 62, -1, -1, -1, -1 }, 
                                                                                           new int[] { 6, 26, 46, 66, -1, -1, -1 }, 
                                                                                           new int[] { 6, 26, 48, 70, -1, -1, -1 }, 
                                                                                           new int[] { 6, 26, 50, 74, -1, -1, -1 }, 
                                                                                           new int[] { 6, 30, 54, 78, -1, -1, -1 }, 
                                                                                           new int[] { 6, 30, 56, 82, -1, -1, -1 }, 
                                                                                           new int[] { 6, 30, 58, 86, -1, -1, -1 }, 
                                                                                           new int[] { 6, 34, 62, 90, -1, -1, -1 }, 
                                                                                           new int[] { 6, 28, 50, 72, 94, -1, -1 }, 
                                                                                           new int[] { 6, 26, 50, 74, 98, -1, -1 }, 
                                                                                           new int[] { 6, 30, 54, 78, 102, -1, -1 }, 
                                                                                           new int[] { 6, 28, 54, 80, 106, -1, -1 }, 
                                                                                           new int[] { 6, 32, 58, 84, 110, -1, -1 }, 
                                                                                           new int[] { 6, 30, 58, 86, 114, -1, -1 }, 
                                                                                           new int[] { 6, 34, 62, 90, 118, -1, -1 }, 
                                                                                           new int[] { 6, 26, 50, 74, 98, 122, -1 }, 
                                                                                           new int[] { 6, 30, 54, 78, 102, 126, -1 },
                                                                                           new int[] { 6, 26, 52, 78, 104, 130, -1 }, 
                                                                                           new int[] { 6, 30, 56, 82, 108, 134, -1 }, 
                                                                                           new int[] { 6, 34, 60, 86, 112, 138, -1 },
                                                                                           new int[] { 6, 30, 58, 86, 114, 142, -1 },
                                                                                           new int[] { 6, 34, 62, 90, 118, 146, -1 }, 
                                                                                           new int[] { 6, 30, 54, 78, 102, 126, 150 },
                                                                                           new int[] { 6, 24, 50, 76, 102, 128, 154 }, 
                                                                                           new int[] { 6, 28, 54, 80, 106, 132, 158 }, 
                                                                                           new int[] { 6, 32, 58, 84, 110, 136, 162 }, 
                                                                                           new int[] { 6, 26, 54, 82, 110, 138, 166 }, 
                                                                                           new int[] { 6, 30, 58, 86, 114, 142, 170 }
                                                                                        };

      // Type info cells at the left top corner.
      private static readonly int[][] TYPE_INFO_COORDINATES = new int[][]
                                                                 {
                                                                    new int[] { 8, 0 }, 
                                                                    new int[] { 8, 1 }, 
                                                                    new int[] { 8, 2 }, 
                                                                    new int[] { 8, 3 }, 
                                                                    new int[] { 8, 4 }, 
                                                                    new int[] { 8, 5 }, 
                                                                    new int[] { 8, 7 }, 
                                                                    new int[] { 8, 8 }, 
                                                                    new int[] { 7, 8 }, 
                                                                    new int[] { 5, 8 }, 
                                                                    new int[] { 4, 8 }, 
                                                                    new int[] { 3, 8 }, 
                                                                    new int[] { 2, 8 }, 
                                                                    new int[] { 1, 8 }, 
                                                                    new int[] { 0, 8 }
                                                                 };

      // From Appendix D in JISX0510:2004 (p. 67)
      private const int VERSION_INFO_POLY = 0x1f25; // 1 1111 0010 0101

      // From Appendix C in JISX0510:2004 (p.65).
      private const int TYPE_INFO_POLY = 0x537;
      private const int TYPE_INFO_MASK_PATTERN = 0x5412;

      /// <summary>
      /// Set all cells to 2.  2 means that the cell is empty (not set yet).
      ///
      /// JAVAPORT: We shouldn't need to do this at all. The code should be rewritten to begin encoding
      /// with the ByteMatrix initialized all to zero.
      /// </summary>
      /// <param name="matrix">The matrix.</param>
      public static void clearMatrix(ByteMatrix matrix)
      {
         matrix.clear(2);
      }

      /// <summary>
      /// Build 2D matrix of QR Code from "dataBits" with "ecLevel", "version" and "getMaskPattern". On
      /// success, store the result in "matrix" and return true.
      /// </summary>
      /// <param name="dataBits">The data bits.</param>
      /// <param name="ecLevel">The ec level.</param>
      /// <param name="version">The version.</param>
      /// <param name="maskPattern">The mask pattern.</param>
      /// <param name="matrix">The matrix.</param>
      public static void buildMatrix(BitArray dataBits, ErrorCorrectionLevel ecLevel, Version version, int maskPattern, ByteMatrix matrix)
      {
         clearMatrix(matrix);
         embedBasicPatterns(version, matrix);
         // Type information appear with any version.
         embedTypeInfo(ecLevel, maskPattern, matrix);
         // Version info appear if version >= 7.
         maybeEmbedVersionInfo(version, matrix);
         // Data should be embedded at end.
         embedDataBits(dataBits, maskPattern, matrix);
      }

      /// <summary>
      /// Embed basic patterns. On success, modify the matrix and return true.
      /// The basic patterns are:
      /// - Position detection patterns
      /// - Timing patterns
      /// - Dark dot at the left bottom corner
      /// - Position adjustment patterns, if need be
      /// </summary>
      /// <param name="version">The version.</param>
      /// <param name="matrix">The matrix.</param>
      public static void embedBasicPatterns(Version version, ByteMatrix matrix)
      {
         // Let's get started with embedding big squares at corners.
         embedPositionDetectionPatternsAndSeparators(matrix);
         // Then, embed the dark dot at the left bottom corner.
         embedDarkDotAtLeftBottomCorner(matrix);

         // Position adjustment patterns appear if version >= 2.
         maybeEmbedPositionAdjustmentPatterns(version, matrix);
         // Timing patterns should be embedded after position adj. patterns.
         embedTimingPatterns(matrix);
      }

      /// <summary>
      /// Embed type information. On success, modify the matrix.
      /// </summary>
      /// <param name="ecLevel">The ec level.</param>
      /// <param name="maskPattern">The mask pattern.</param>
      /// <param name="matrix">The matrix.</param>
      public static void embedTypeInfo(ErrorCorrectionLevel ecLevel, int maskPattern, ByteMatrix matrix)
      {
         BitArray typeInfoBits = new BitArray();
         makeTypeInfoBits(ecLevel, maskPattern, typeInfoBits);

         for (int i = 0; i < typeInfoBits.Size; ++i)
         {
            // Place bits in LSB to MSB order.  LSB (least significant bit) is the last value in
            // "typeInfoBits".
            int bit = typeInfoBits[typeInfoBits.Size - 1 - i] ? 1 : 0;

            // Type info bits at the left top corner. See 8.9 of JISX0510:2004 (p.46).
            int x1 = TYPE_INFO_COORDINATES[i][0];
            int y1 = TYPE_INFO_COORDINATES[i][1];
            matrix[x1, y1] = bit;

            if (i < 8)
            {
               // Right top corner.
               int x2 = matrix.Width - i - 1;
               int y2 = 8;
               matrix[x2, y2] = bit;
            }
            else
            {
               // Left bottom corner.
               int x2 = 8;
               int y2 = matrix.Height - 7 + (i - 8);
               matrix[x2, y2] = bit;
            }
         }
      }

      /// <summary>
      /// Embed version information if need be. On success, modify the matrix and return true.
      /// See 8.10 of JISX0510:2004 (p.47) for how to embed version information.
      /// </summary>
      /// <param name="version">The version.</param>
      /// <param name="matrix">The matrix.</param>
      public static void maybeEmbedVersionInfo(Version version, ByteMatrix matrix)
      {
         if (version.VersionNumber < 7)
         {
            // Version info is necessary if version >= 7.
            return; // Don't need version info.
         }
         BitArray versionInfoBits = new BitArray();
         makeVersionInfoBits(version, versionInfoBits);

         int bitIndex = 6 * 3 - 1; // It will decrease from 17 to 0.
         for (int i = 0; i < 6; ++i)
         {
            for (int j = 0; j < 3; ++j)
            {
               // Place bits in LSB (least significant bit) to MSB order.
               var bit = versionInfoBits[bitIndex] ? 1 : 0;
               bitIndex--;
               // Left bottom corner.
               matrix[i, matrix.Height - 11 + j] = bit;
               // Right bottom corner.
               matrix[matrix.Height - 11 + j, i] = bit;
            }
         }
      }

      /// <summary>
      /// Embed "dataBits" using "getMaskPattern". On success, modify the matrix and return true.
      /// For debugging purposes, it skips masking process if "getMaskPattern" is -1.
      /// See 8.7 of JISX0510:2004 (p.38) for how to embed data bits.
      /// </summary>
      /// <param name="dataBits">The data bits.</param>
      /// <param name="maskPattern">The mask pattern.</param>
      /// <param name="matrix">The matrix.</param>
      public static void embedDataBits(BitArray dataBits, int maskPattern, ByteMatrix matrix)
      {
         int bitIndex = 0;
         int direction = -1;
         // Start from the right bottom cell.
         int x = matrix.Width - 1;
         int y = matrix.Height - 1;
         while (x > 0)
         {
            // Skip the vertical timing pattern.
            if (x == 6)
            {
               x -= 1;
            }
            while (y >= 0 && y < matrix.Height)
            {
               for (int i = 0; i < 2; ++i)
               {
                  int xx = x - i;
                  // Skip the cell if it's not empty.
                  if (!isEmpty(matrix[xx, y]))
                  {
                     continue;
                  }
                  int bit;
                  if (bitIndex < dataBits.Size)
                  {
                     bit = dataBits[bitIndex] ? 1 : 0;
                     ++bitIndex;
                  }
                  else
                  {
                     // Padding bit. If there is no bit left, we'll fill the left cells with 0, as described
                     // in 8.4.9 of JISX0510:2004 (p. 24).
                     bit = 0;
                  }

                  // Skip masking if mask_pattern is -1.
                  if (maskPattern != -1)
                  {
                     if (MaskUtil.getDataMaskBit(maskPattern, xx, y))
                     {
                        bit ^= 0x1;
                     }
                  }
                  matrix[xx, y] = bit;
               }
               y += direction;
            }
            direction = -direction; // Reverse the direction.
            y += direction;
            x -= 2; // Move to the left.
         }
         // All bits should be consumed.
         if (bitIndex != dataBits.Size)
         {
            throw new WriterException("Not all bits consumed: " + bitIndex + '/' + dataBits.Size);
         }
      }

      /// <summary>
      /// Return the position of the most significant bit set (to one) in the "value". The most
      /// significant bit is position 32. If there is no bit set, return 0. Examples:
      /// - findMSBSet(0) => 0
      /// - findMSBSet(1) => 1
      /// - findMSBSet(255) => 8
      /// </summary>
      /// <param name="value_Renamed">The value_ renamed.</param>
      /// <returns></returns>
      public static int findMSBSet(int value_Renamed)
      {
         int numDigits = 0;
         while (value_Renamed != 0)
         {
            value_Renamed = (int)((uint)value_Renamed >> 1);
            ++numDigits;
         }
         return numDigits;
      }

      /// <summary>
      /// Calculate BCH (Bose-Chaudhuri-Hocquenghem) code for "value" using polynomial "poly". The BCH
      /// code is used for encoding type information and version information.
      /// Example: Calculation of version information of 7.
      /// f(x) is created from 7.
      ///   - 7 = 000111 in 6 bits
      ///   - f(x) = x^2 + x^2 + x^1
      /// g(x) is given by the standard (p. 67)
      ///   - g(x) = x^12 + x^11 + x^10 + x^9 + x^8 + x^5 + x^2 + 1
      /// Multiply f(x) by x^(18 - 6)
      ///   - f'(x) = f(x) * x^(18 - 6)
      ///   - f'(x) = x^14 + x^13 + x^12
      /// Calculate the remainder of f'(x) / g(x)
      ///         x^2
      ///         __________________________________________________
      ///   g(x) )x^14 + x^13 + x^12
      ///         x^14 + x^13 + x^12 + x^11 + x^10 + x^7 + x^4 + x^2
      ///         --------------------------------------------------
      ///                              x^11 + x^10 + x^7 + x^4 + x^2
      ///
      /// The remainder is x^11 + x^10 + x^7 + x^4 + x^2
      /// Encode it in binary: 110010010100
      /// The return value is 0xc94 (1100 1001 0100)
      ///
      /// Since all coefficients in the polynomials are 1 or 0, we can do the calculation by bit
      /// operations. We don't care if cofficients are positive or negative.
      /// </summary>
      /// <param name="valueCode">The value.</param>
      /// <param name="poly">The poly.</param>
      /// <returns></returns>
      public static int calculateBCHCode(int valueCode, int poly)
      {
         // If poly is "1 1111 0010 0101" (version info poly), msbSetInPoly is 13. We'll subtract 1
         // from 13 to make it 12.
         int msbSetInPoly = findMSBSet(poly);
         valueCode <<= msbSetInPoly - 1;
         // Do the division business using exclusive-or operations.
         while (findMSBSet(valueCode) >= msbSetInPoly)
         {
            valueCode ^= poly << (findMSBSet(valueCode) - msbSetInPoly);
         }
         // Now the "value" is the remainder (i.e. the BCH code)
         return valueCode;
      }

      /// <summary>
      /// Make bit vector of type information. On success, store the result in "bits" and return true.
      /// Encode error correction level and mask pattern. See 8.9 of
      /// JISX0510:2004 (p.45) for details.
      /// </summary>
      /// <param name="ecLevel">The ec level.</param>
      /// <param name="maskPattern">The mask pattern.</param>
      /// <param name="bits">The bits.</param>
      public static void makeTypeInfoBits(ErrorCorrectionLevel ecLevel, int maskPattern, BitArray bits)
      {
         if (!QRCode.isValidMaskPattern(maskPattern))
         {
            throw new WriterException("Invalid mask pattern");
         }
         int typeInfo = (ecLevel.Bits << 3) | maskPattern;
         bits.appendBits(typeInfo, 5);

         int bchCode = calculateBCHCode(typeInfo, TYPE_INFO_POLY);
         bits.appendBits(bchCode, 10);

         BitArray maskBits = new BitArray();
         maskBits.appendBits(TYPE_INFO_MASK_PATTERN, 15);
         bits.xor(maskBits);

         if (bits.Size != 15)
         {
            // Just in case.
            throw new WriterException("should not happen but we got: " + bits.Size);
         }
      }

      /// <summary>
      /// Make bit vector of version information. On success, store the result in "bits" and return true.
      /// See 8.10 of JISX0510:2004 (p.45) for details.
      /// </summary>
      /// <param name="version">The version.</param>
      /// <param name="bits">The bits.</param>
      public static void makeVersionInfoBits(Version version, BitArray bits)
      {
         bits.appendBits(version.VersionNumber, 6);
         int bchCode = calculateBCHCode(version.VersionNumber, VERSION_INFO_POLY);
         bits.appendBits(bchCode, 12);

         if (bits.Size != 18)
         {
            // Just in case.
            throw new WriterException("should not happen but we got: " + bits.Size);
         }
      }

      /// <summary>
      /// Check if "value" is empty.
      /// </summary>
      /// <param name="value">The value.</param>
      /// <returns>
      ///   <c>true</c> if the specified value is empty; otherwise, <c>false</c>.
      /// </returns>
      private static bool isEmpty(int value)
      {
         return value == 2;
      }

      private static void embedTimingPatterns(ByteMatrix matrix)
      {
         // -8 is for skipping position detection patterns (size 7), and two horizontal/vertical
         // separation patterns (size 1). Thus, 8 = 7 + 1.
         for (int i = 8; i < matrix.Width - 8; ++i)
         {
            int bit = (i + 1) % 2;
            // Horizontal line.
            if (isEmpty(matrix[i, 6]))
            {
               matrix[i, 6] = bit;
            }
            // Vertical line.
            if (isEmpty(matrix[6, i]))
            {
               matrix[6, i] = bit;
            }
         }
      }

      /// <summary>
      /// Embed the lonely dark dot at left bottom corner. JISX0510:2004 (p.46)
      /// </summary>
      /// <param name="matrix">The matrix.</param>
      private static void embedDarkDotAtLeftBottomCorner(ByteMatrix matrix)
      {
         if (matrix[8, matrix.Height - 8] == 0)
         {
            throw new WriterException();
         }
         matrix[8, matrix.Height - 8] = 1;
      }

      private static void embedHorizontalSeparationPattern(int xStart, int yStart, ByteMatrix matrix)
      {
         for (int x = 0; x < 8; ++x)
         {
            if (!isEmpty(matrix[xStart + x, yStart]))
            {
               throw new WriterException();
            }
            matrix[xStart + x, yStart] = 0;
         }
      }

      private static void embedVerticalSeparationPattern(int xStart, int yStart, ByteMatrix matrix)
      {
         for (int y = 0; y < 7; ++y)
         {
            if (!isEmpty(matrix[xStart, yStart + y]))
            {
               throw new WriterException();
            }
            matrix[xStart, yStart + y] = 0;
         }
      }

      /// <summary>
      /// Note that we cannot unify the function with embedPositionDetectionPattern() despite they are
      /// almost identical, since we cannot write a function that takes 2D arrays in different sizes in
      /// C/C++. We should live with the fact.
      /// </summary>
      /// <param name="xStart">The x start.</param>
      /// <param name="yStart">The y start.</param>
      /// <param name="matrix">The matrix.</param>
      private static void embedPositionAdjustmentPattern(int xStart, int yStart, ByteMatrix matrix)
      {
         for (int y = 0; y < 5; ++y)
         {
            for (int x = 0; x < 5; ++x)
            {
               matrix[xStart + x, yStart + y] = POSITION_ADJUSTMENT_PATTERN[y][x];
            }
         }
      }

      private static void embedPositionDetectionPattern(int xStart, int yStart, ByteMatrix matrix)
      {
         for (int y = 0; y < 7; ++y)
         {
            for (int x = 0; x < 7; ++x)
            {
               matrix[xStart + x, yStart + y] = POSITION_DETECTION_PATTERN[y][x];
            }
         }
      }

      /// <summary>
      /// Embed position detection patterns and surrounding vertical/horizontal separators.
      /// </summary>
      /// <param name="matrix">The matrix.</param>
      private static void embedPositionDetectionPatternsAndSeparators(ByteMatrix matrix)
      {
         // Embed three big squares at corners.
         int pdpWidth = POSITION_DETECTION_PATTERN[0].Length;
         // Left top corner.
         embedPositionDetectionPattern(0, 0, matrix);
         // Right top corner.
         embedPositionDetectionPattern(matrix.Width - pdpWidth, 0, matrix);
         // Left bottom corner.
         embedPositionDetectionPattern(0, matrix.Width - pdpWidth, matrix);

         // Embed horizontal separation patterns around the squares.
         const int hspWidth = 8;
         // Left top corner.
         embedHorizontalSeparationPattern(0, hspWidth - 1, matrix);
         // Right top corner.
         embedHorizontalSeparationPattern(matrix.Width - hspWidth, hspWidth - 1, matrix);
         // Left bottom corner.
         embedHorizontalSeparationPattern(0, matrix.Width - hspWidth, matrix);

         // Embed vertical separation patterns around the squares.
         const int vspSize = 7;
         // Left top corner.
         embedVerticalSeparationPattern(vspSize, 0, matrix);
         // Right top corner.
         embedVerticalSeparationPattern(matrix.Height - vspSize - 1, 0, matrix);
         // Left bottom corner.
         embedVerticalSeparationPattern(vspSize, matrix.Height - vspSize, matrix);
      }

      /// <summary>
      /// Embed position adjustment patterns if need be.
      /// </summary>
      /// <param name="version">The version.</param>
      /// <param name="matrix">The matrix.</param>
      private static void maybeEmbedPositionAdjustmentPatterns(Version version, ByteMatrix matrix)
      {
         if (version.VersionNumber < 2)
         {
            // The patterns appear if version >= 2
            return;
         }
         int index = version.VersionNumber - 1;
         int[] coordinates = POSITION_ADJUSTMENT_PATTERN_COORDINATE_TABLE[index];
         int numCoordinates = POSITION_ADJUSTMENT_PATTERN_COORDINATE_TABLE[index].Length;
         for (int i = 0; i < numCoordinates; ++i)
         {
            for (int j = 0; j < numCoordinates; ++j)
            {
               int y = coordinates[i];
               int x = coordinates[j];
               if (x == -1 || y == -1)
               {
                  continue;
               }
               // If the cell is unset, we embed the position adjustment pattern here.
               if (isEmpty(matrix[x, y]))
               {
                  // -2 is necessary since the x/y coordinates point to the center of the pattern, not the
                  // left top corner.
                  embedPositionAdjustmentPattern(x - 2, y - 2, matrix);
               }
            }
         }
      }
   }
}